IEEE 802.16a is a wireless communications specification for metropolitan area networks (MANs). The 802.16a standard was developed for wireless MANs operating on licensed and unlicensed radio-frequency (RF) bands between 2 GHz and 11 GHz, at data speeds of up to 75 megabits per second (Mbps), with low latency and efficient use of spectrum space. Security is enhanced by encryption features. The contention symbols are based on OFDM (orthogonal frequency division multiplexing) symbols similar in construction to 802.16a (OFDM mode) or 802.11a symbols.
The 802.16a focused contention transmission includes two (2) consecutive contention symbols, each beginning with a cyclic prefix and containing two hundred (200) usable subcarriers. The subcarriers are divided into fifty (50) contention channels of four (4) subcarriers apiece. The lowest numbered contention channel uses subcarriers 0, 50, 100 and 150. The highest numbered contention channel uses subcarriers 49, 99, 149 and 199. The symbol timeline is shown in FIG. 1. As shown in FIG. 1, under the 802.16a standard, the maximum permissible propagation delay for effective reception of symbols at a receiver is Tg, which represents the time it takes to transmit the cyclic prefix. In various instances, such maximum permissible propagation delay may be exceeded thereby rendering reception of symbols by the receiver ineffective.
Hence, it would be desirable to provide methods and systems that are capable of, amongst other things, providing channel access in an efficient manner and extending the maximum supported propagation delay.